spa112: possible to choose between 2 sip servers on one line?

[Nicksreason]

Id like to be able to select between two voip providers on one spa112 line. Is there a good way to do this?

[Howard Wittenberg]

Id like to be able to select between two voip providers on one spa112 line. Is there a good way to do this?

Setup the two providers on a PBX and have your SPA112 an extension on the PBX. You can setup your own Asterisk based PBX for a pretty minimal budget.

The reason you can not do this directly on a SPA112 is that voip providers require caller authentication (userid / password). The SPA112 ATA has no provision to do this on a single line.

An older ATA, the SPA3102, does have a provision to configure outbound only voip providers (up to four) as long as the voip provider does not require registration prior to the outgoing call.

[Howard Wittenberg]

Dan, 

Thanks for pointing out those dial plan parameters.  I tested it again today with my SPA3102 and analyzed the result with a WireShark sip trace. It still fails with my SPA3102. Perhaps it would be different with a SPA112.

With the SPA3102 this is the difference I observed between a good call using a SPA3102 gateway configuration and a rejected call using the usr=; pwd=; nat parameters in the dial plan:
In the header of the INVITE of the rejected call:
1. the From: line did not reflect the usr=nnnnnnn entry or the sip_proxy where the call was sent
2. the Contact: line did not reflect the usr=nnnnnnn entry.

The DNS was correct and the INVITE was sent to the correct ip address and port number. In the header the Proxy-Authorization line was the same as in the completed call.

The user name parameter must be usr= not uid= (as stated in some documentation), otherwise the correct username= entry in the Proxy-Authorization line of the INVITE header  is not correct.

I tested with the following dial plan:
(<#9,:>xx.<:@sip.callwithus.com;usr=nnnnnnnn;pwd=nnnnnnnn;nat>|<#8,:>xx.<:@gw2>|xx.)

Perhaps the sophistication of various voip provider's authentication will vary and the technique will not fail if only the Proxy-Authorization information is authenticated for a caller.

[Dan Lukes]

I tested it so long time ago, so I remember no details, but there may be a condition that may affect the results.

If the usr/pwd used in DialPlan of Line 1 is the same as the registration credentials used on Ext 2 you may got different results from the case when usr/pwd is unrelated to a credentials configured on a extension.

[Nicksreason]

Thanks Howard,

I looked into this first with FreePBX or Asterisk but decided it meant I had to maintain (and power) a computer to keep it alive. I liked the simplicity of a little box like the SPA112 only. I was looking into a Raspberry Pi for the FreePBX. What turned me away from that idea was a few reports of the SD card getting corrupted upon power outages and writing. I'd still like to try this idea though.

[Dan Lukes]

99hwittenb  says true, but there's some not so bright light on the end of tunnel.

Read DialPlan string for SPA122 with <@sip-operator;uid/usr=; pwd= > including the comments.

Note such feature needs to be considered undocumented. It may or may not work for you. Just try it if interested.